Distillation method



u 1944- c. E. HEMMINGER ,5

DISTILLATION METHOD Filed Dec. 9, 1939 50 1W 4 5Q I ue 1 cAs 007-427 Patented June 6, 1944 DISTILLATION METHOD Charles E. Hemminger, Westfield, N. 5., assignor to Standard Oil Development Company, a corporation of Delaware Application December 9, 1939, Serial No. 308,369

(ill. 196-435) 1 Claim.

The present invention relates to the treatment of hydrocarbon oils. More particularly, the present invention relates to improvements in the distillation of heavy crudes so as to recover a maximum amount of gas oil with a minimum amount of cracking and. coke formation.

It is well known that in the distillation of a heavy reduced crude to recover gas oil, according to prior practice, large amounts of gasoline are produced by cracking. Since this gasoline is produced by thermal cracking, the octane number of the same is relatively low, usually in the neighborhood of 60-65 as determined by the A. S. T. M. method. Furthermore, in recovering a gas oil from a heavy reduced crude, the process results in the deposition of a hard adherent coke which necessitates frequent shut-downs to remove the same from soaking drums and the like. Furthermore, the gas oihrecovered from this type of operation is a poor cracking stock because it has become degraded during the distillation oper ation.

It is a principal object of the present invention to distill a heavy reduced crude such as 18% bottoms from east Texas crude (that is the residue remaining after 82% of the original crude has been removed by distillation) under conditions such that the gas oil is removed from the reduced crude without substantial cracking and according to one form of my invention, this result is accomv plished by simply heating the reduced crude sufficiently high so that when steam is admixed with the heated reduced crude, distillation of the gas oil takes place and the gas vapors are rapidly removed from the distillation zone.

A secondary object of my invention is to cause the residue of the reduced crude remaining, after removal of the gas oil cut, to pass through a coking zone which is heated by direct steam and also by radiation from fired tubes, whereby a relatively fiufiy or porous coke is formed which coke descends to the bottom of the coking zone and is discharged from the bottom thereof.

Other and further objects of my present invention will be obvious from the ensuing description.

To the accomplishment of the foregoing and related ends, I provide a process and apparatus which are fully disclosed in the present description and claims, reference being had to the accompanying drawing.

Referring to the drawing, Figure 1 shows a vertical perspective, broken in part, of a distillation vessel in which my process may be carried out.

Referring more particularly to the drawing, a

heavy reduced crude such as an east Texas crude from which approximately 82% has been removed by distillation, which residue or reduced crude has an A. P. I. gravity of 17, is fed from line I to a header or manifold 2. The stock is at a temperature of about 900 F. while under a pressure of about 3 to 50 pounds per square inch gauge in line I. The heated oil is discharged into a vessel 6 from manifold 2 through branch pipes 3, and nozzles 4. The spray heads or nozzles 4 carry perforations of about 1% to /8 inch in diameter in the bases or spray ends thereof, and the oil is sprayed from spray heads 4 into the interior of vessel 6 in the form of fine streams. To assist in the spraying operation, steam is forced into the spray heads through branch lines 7.

As can be seen from the drawing, the vessel 6 is so formed and constructed that the upper wall 18 slopes outwardly while the lower wall I i slopes inwardly. Surrounding the wall I0 is a manifold pipe M in communication with a series of secondary manifold pipes l5, which latter pipes are in turn in communication with branch pipes 16 projecting into the interior of the vessel 6. These branch pipes 16 are disposed obliquely, with respect to sloping wall It, i. e. are not perpendicular to wall ID, of vessel 5. The number of manifolds l5 may vary from say 4 to 16 or 20 and are disposed preferably at equally spaced positions around the wall 10. The number of branch pipes i6 attached to a manifold [5 may also vary from 3 or 4 to 8 or 10. Steam is fed to manifold l4 through valved line 20.

Another manifold pipe 25 is disposed about the exterior of vessel 6 as shown. This manifold has a plurality of branch pipes 26 in communication therewith which branch pipes project into the vessel 6, extend upwardly, substantially parallel to and in spaced relation with the wall It, say 4 to 6 inches removed therefrom, then project out of the vessel and terminate in upper exhaust manifold 36. The number of pipes 26 will vary depending on the dimensions of the vessel 6. Good results are obtained by spacing the pipes 26 about 6 and 12 inches apart around the whole Wall surface. The pipes 26 are preferably shaped from KAZS alloy steel and may have an internal diameter of from about 1 to 2 inches. A combustible gas and air are fed into lower manifold 25 through feed line 3|, are burned in pipes 26 say, a gas such .as water gas, natural gas, or any fuel gas is mixed with suflicient air to cause oxidation of the combustible material in the fuel gas, preheated and pumped into manifold 25 at a temperature of about 800 F. The main combustion occurs within those portions of the several tubes disposed within the vessel andea uniform temperature of about 1400" F. is reached within the tubes. A portion of the heat of combustion is radiated toward the center of the vessel. The steam fed into the system through line 20 may be at an inlet temperature of about 800 F. and this steam is discharged from pipes l6 which terminate in closeproximity to tubes 26,111 flowing streams, in contacting relationship with the surfaces of the tubes 26 and is thereby heated to a temperature of 1000 F. or higher. V

Referring back to the atomized oil issuing from spray heads 4, the said oil proceeds downwardly and in the vicinity of V, oil vapors are released from the droplets of heavy oil due to the radiant heat from pipes 26, the superheated steam and countercurrently flowing oil vapors from lower levels encountered in this environment. The mixture of oil vapors and steam is withdrawn through line 50. The heavy oil conexample, any tendency of coke to deposit on the tubes 26 can be counteracted by periodically cooling the tubes by circulation therethrough of a cooling fluid whereupon the tubes will be caused to contract and any coke adhering to the tube surface will be dislodged by expansion and contraction of the tube surfaces. Of course, mechanical scraping means could also be employed for this same purpose of removing coke from the tubes, i. e. either tubes 26 or the ends of pipe 16 Q lying within the vessel 6.

tinues in its descent from V downwardly toward the zone C and in so doing accumulates heat suflicient to reduce the oil to a hard coke and vapors containing principally gas oil with'minor amounts of gasoline and normally gaseous hydrocarbons. Normally gaseous hydrocarbons, gasoline, vapors, gas oil vapors and steam pass upwardly through vessel 6 and are discharged through line 50 and then pass to a fractionating system (not'shown). The gas oil obtained forms a good cracking stock.

The coke produced drops to the region represented generally by R in which is located a. conical element 60 mounted on a rotatable shaft. The cone 60 is disposed eccentrically with respect' to the vertical axis of the base 62 of vessel 6. Bevel gear 64 is securely mounted on shaft GI and engages pinion 63 securely mounted on shaft 65, a projection of which shaft is attached to a driving means (not shown). Rotation of grinding cone 60 causes the coke conglomerates to be crushed. The coke is recoveredthrough line 66. Steam at about 800 F. is admitted through line 68 to assist the vaporization operation. a f

The precise details of operation and/or construction herein set forth. are purely illustrative and do not impose any limitation onmy invene tion since numerous modifications of my invention falling within the spirit thereof will have been suggested to those familiar with this'art after they have read the present disclosure. For

Another modification of my invention involves substituting for the metal tubes 26, a refractory brick-lik material having restricted passages therein.

To recapitulate, the present invention comprises a process in which a heavy stock such as a reduced crude is distilled without substantial cracking to form gas oil, gasoline and coke. The distillation vessel is preferably one with sloping sides, its largest cross-sectional area being in a plane between the top and bottom of the vessel. The advantage of this type of construction is that the oil from spray heads 4 does not impinge upon the walls of the vessel. Furthermore, the vapors are rapidly removed from the distillation zone and overheating is prevented.

What I claim is:

' The continuous method of distilling and coking a heavy residual hydrocarbon oil which comprises discharging the said oil in heated condition and in the form of droplets into the upper portion of a distillation zone, gravitating the said oil through said zone while contacting the said oil with upfiowing superheated steam to cause the rapid release of gas oil and lighter hydrocarbons from said 011 without substantial cracking of said gas oil, gravitating the residual oil from the distill-ation'zone into and through a coking zone, the oil encountering progressively increasing cross-sectional areas as it gravitates through the said zones whereby the tendency of oil material and wet coky material to adhere to confining walls of said zones is substantially obviated, supplying additional heat to said oil by burning a gas within said coking zone but out of contact with said oil, injecting direct superheated steam into said oil at a plurality of vertically'and circumferentially spaced points along the periphery of the distillation and coking zones as the oil passes through said zones thereby directing said oil away from the said confining walls and also heating it to produce further quantities of gas oil and coke, recovering gas oil and lighterrhydrocarbons as an overhead product from both of said zones and coke as a bottoms from said cokmg zone. a t

CHARLES E. HEMMINGER. 

